Sunday, 26 December 2010

How long do you need to boil IPA?

IPA. It's a while since I wrote anything about IPA. (Other than it not being a strong beer.) Time for an amusing little text from the early days of the India trade.

The piece is really about boiling and how long a wort needs to be boiled to get the required preservative qualities out of the hops.

"OF BOILING.

About this, also, there are various opinions; many think that long boiling, particularly of the last worts, tends to make the beer keep sound, I am not aware, however, of any preservative quality, imparted by long boiling; but, on the contrary, I have seen grey beer produced, after very long boiling ; the result, probably, of some injurious extract from the hops. The high colour produced by bad boiling, is a mere eye sore. The brick red I have seen come upon very pale worts, during fermentation. I have also seen ale, intended to be pale, made of a brick-reddish colour, after too long boiling. Whether this proceeded, however, from the long boiling, or from the copper not being altogether safe before turning out, I cannot say. Long boiling undoubtedly adds to the strength of the worts by evaporation, and thus enables us, where there is no raw wort, to take a few barrels more from our goods. I doubt very much, however, whether the expense of coals and time does not more than counterbalance the advantage.

In 1832, I brewed a small gyle of pale beer for the India market. The first worts were boiled one hour, the second one and a half hour. I beg leave to subjoin the report made upon it in Calcutta.

"Calcutta, 8th August, 1832. — Report on two hogsheads of Black's pale ale, examined in the custom house godowns of Messrs. Lyall, Matheson and Co. —Two hogsheads of Black's pale ale. — This pale ale, of superior quality, is well adapted for the India market, both in colour, body, and flavour.

(Signed) John Brown And Co.,
Coopers to the Honour able Company.

Another lot of this same beer went to Messrs. Watson and Co., and I beg leave, also, to insert a short extract of their letter to me, of date, Calcutta, 9th April, 1833.

"We wrote to you on the 17th of November to which we refer you.—Your beer is now ripe, and confirms what we then wrote you; it is really most excellent, and, as such, we are disposing of it in small quantities, so as it may be known."

This, at all events, proves that long boiling is not essential to the preservation of beer; and I have come to the conclusion, that long boiling can do no good, but may do harm. Unless, therefore, longer time should be required for strength, I should say, that one hour's boiling will sufficiently break the first worts, and two hours, at the utmost, will do the same by any other wort."
"A practical treatise on brewing" by William Black, 1835, pages 39-41.

There you have. An hour's boil for the first wort and two hours for the rest is plenty to preserve a beer on the journey to India.

According to Wikipedia and at least two online dictionaries, "godown" is still used in Indian English as a term for warehouse.

Modern brewing practice recommends a wort boil of no more than 2 hours for maximum alpha acid extraction. Beyond that, there's no further extraction and the alpha acids (responsible for hop bitterness and antibacterial properties) start to degrade. So, at least in that respect Black is spot on.

I've also seen similar "brick red" (medium/dark amber - 20-30 SRM) colors imparted to beers made using pale/light amber malt due to long boil times, especially in highly hopped brews.

Indirectly, Black implies that a well-made IPA of the period shouldn't be so dark. Perhaps 10-20 SRM?

He also indirectly answers a question I've had about historical brewing practice. Before the 20th century, it seems that that the worts for some beers were boiled for most of a day, if not longer. Based on Black's comments, it would seem to be early 19th century conventional brewing wisdom that a long boil time helped preserve the beer.

Finally, there is a part of your post which begs a further question: What does Black mean when he mentions "grey" beer?

Does this refer to cloudy/hazed beer or to an actual gray color imparted to the beer by long boil times? My guess is the first option.